That Which Remains
by introspecticskeptic
Summary: As Derek comes to terms with his mortality, he finds himself suddenly unsure of what he is outside of the Sole Survivor of both Vault 111 and of the Great War.


In all his life, Derek never thought he'd live to see this moment. He wore a constant target on his back, either for an enemy solider or for one of the many things hunting him throughout the Commonwealth. He'd stared down Death more than once and had walked – or sometimes limped – away victorious over him. So, in his wildest dreams, he never could have conceived of this day coming.

"I'm going grey. Holy shit." MacCready looked up from his sink where he was brushing his teeth. He raised an eyebrow and continued scrubbing. Derek tuned his head to various angles, but everything confirmed it. His once dark blonde hair now had a decided amount of grey in it.

"Derek, it's not that big a deal. Really."

"It is!" Derek plucked a hair out and held it before him as though it was a key piece of evidence, "this means that not only am I old, but that everyone and everything now knows I'm old!" MacCready pulled the hair from Derek's fingers and tossed it aside.

"There, now no one cares that you're old." He rinsed his toothbrush and again marveled at the fact that they had plumbing and running water.

Derek had spent months on Spectacle building something, and the only companion he had let visit before revealing it had been Ada. The house was a marvel of engineering, so far as MacCready was concerned. It had running water, working electricity, and even had a play area for Shaun and Duncan.

"But they will! Look at Longfellow, every time we travel together, people always size him up. What if they now think that I'm weak enough to attack?" MacCready threw his shirt into the hamper (who knew that those huge mechanical things that held clothing could even work?) and headed upstairs to their bedroom, Derek following close behind.

"Well, did they ever decide he was an easy mark?" Derek sat on the bed and stared out the window overlooking the sound between the island and the mainland.

"No, but that doesn't mean that they wouldn't." MacCready laughed, for as long as he and Derek had been companions and lover, he still sometimes couldn't understand his love's logic.

"So, you're telling me that you're freaking out over the chance someone thinks you're weak?" Pulling on a thick sweater, MacCready stuck his head back out of the closet and watched as Derek thought about it.

"When you put it that way…" He rolled his eyes and stepped back into the closet to grab a pair of pants to throw on. Now with a pair of jeans and his boots, MacCready returned to Derek.

"Derek, it doesn't matter what people think. Just look at me! I look like a loser with a big nose and bad teeth. But you saw past that and still chose to love the man I am. Not what I looked like." Derek smiled up at MacCready. But the smile was thin and faded quickly, returning Derek to his musings through the window. Glancing out the door, MacCready shut the door and sat on the bed next to Derek.

"Alright, what's really bothering you. Normally sappy things like that make you at least blush."

"All my life, I always figured I would die young. I was a soldier doing things that no man should ever do. My life was only as good as my skills. But I survived. I married Nora, retired, had a kid. And I lived my life for one glorious year. But then the bombs fell.

I figured I would die then with Nora and Shaun by my side. But I didn't. Nora was killed by Kellogg and Shaun was stolen from me, but I survived. And then I woke back up nearly eighty years later. I stumbled into a world where I should have died at every turn. I found Kellogg, infiltrated the Institute, took down both the Institute and the Brotherhood. I left Shaun, my son, the one thing I had left…" He shook his head and blinked the tears in his eyes away.

"I killed my son. I left him to die in the cursed place. But I survived. I always survive."

"That sounds like a good thing, I mean, dying is sorta the opposite of what most people want." Derek rose to his feet and crossed to the window. He could still hear the rush of traffic, the roar of civilization, in his head. But he knew that they were all ghosts now. Everything had died, the people, the technology, the world.

"But I survived."

"Derek, do you want to die?" He could hear the pain in MacCready's voice. He wanted to rush over and swoop him off his feet, affirming his love for him. But he did none of those things.

"I don't want to be the last one to survive." The sob ripped out of him before he even knew he was crying. Bitter hot tears of fear and rage poured down his face, dampening the newly grey beard on their way out. He sank to his knees, too consumed with pain to care about how humiliating it must have looked. MacCready fell to the floor beside him, holding him as close as he could.

"When Lucy died, I felt the same thing. And on the bad days, I still do." Derek buried his face into MacCready's neck, arms wrapping tightly around his chest as the tears poured even harder. "I'm not going to lie, Derek. Living is hard. But that's why we do it. When all else falls apart, we have to choose to remain."

"I don't know if I want to." The small voice was almost unrecognizable as Derek's. MacCready hugged Derek tighter. He'd never before had seen Derek so hurt. The paternal instincts of MacCready wanted to take Derek and coddle him until he felt better, the soldier in MacCready wanted to punish the weakness so that it went away. MacCready settled for a compromise and slowly began rocking Derek side to side.

"That's alright. You don't have to know right now. That's a question you have all the time in the world to answer. For today though, 'I don't know' is enough." Still rocking, MacCready began softly singing the only lullaby he knew.

He'd heard Lucy sing it one night when Duncan was being fussy, and when it instantly quieted him he had begged her to teach him. She had only taught him a part of it before he had fallen asleep. She hadn't taught him the second half, as the next night they stayed in the metro station where she was killed by the ferals.

He rocked and sang about the loneliness of being left by loved ones. His voice strained to hit the high notes, but he could feel Derek's breathing steady. He restarted the song and was joined this time by Derek who sang along with surprising ease. This time when MacCready reached the end of the part he knew, Derek took over and sang the rest. Finishing the final decrescendo with a soft rumble, Derek finally sat up.

"I don't want to be alone. I don't want to survive if it means that everyone I love is gone." He slowly turned to face MacCready, tears in his eyes. "Promise me that you won't let me survive."

"I can't. I could die tomorrow for all we know. But that doesn't mean you're alone. There's Shaun, and Duncan will need someone to love him. Plus, there's still all your friends back in Sanctuary." Derek frowned and bowed his head, his hair obscuring his face. "Derek, I want you to promise that you won't leave Duncan and Shaun alone. No matter what happens to me, no matter what happens to you, they don't deserve to have both their parents die." MacCready squeezed Derek's slack hand, hoping to convey the importance of the promise.

"I promise. They will never be without love. I will make sure they aren't."

"Thank you, that means so much to me." They hugged again, each reluctant to let go, but soon the sounds of small feet running outside the house gave them the strength to let go. MacCready let Derek stay in their room as he went to go care for their children. Derek returned to looking out the window.

The city he had grown up in the shadows of, the nation he had fought for, the life he had dreamed of were all gone. But the sounds of his kids laughing as his husband chased them made the ruined city seem brighter.

His life wasn't gone, it was changed. And he knew that he would find a way to adapt to it once again. He was Loki, after all, he knew how to change.


End file.
